1. Field of the Invention
The present invention relates generally to fastening devices and, more particularly, to a swivel hoist ring for being removably connected to trench plates.
2. Description of Related Art
Various swivel hoist rings have been implemented in the prior art. U.S. Pat. No. 3,297,293 to Andrews et al. discloses a fastening device comprising an eye member which is pivotally and rotationally mounted onto a bise. The fastening device, however, comprises a relatively small-diameter retaining ring for contacting the base. Horizontal forces exerted onto the fastening device must thus be absorbed by a stud secured into the base and the relatively small-diameter retaining ring. Additionally, removal of the fastening device from the base can only be achieved by using a tool to grip the head of the stud, which is also configured to have a relatively small diameter. If the head of the stud is damaged, or if a wrench is not available for fitting onto the head of the stud, then the fastening device cannot easily be removed.
Trench plates generally comprise rectangular steel members weighing between 5,000 and 9,000 pounds. A typical trench plate may be 8 feet wide by 12 feet long and 2 inches thick. A threaded nut is secured in a middle area of the trench plate, and is adapted for receiving an eye bolt, according to the prior art. The eye bolt comprises an opening, for receiving a cable or other fastening member. Once the eye bolt is threaded into the nut of the trench plate, and is fastened to a cable, for example, the trench plate can be removed. Eye bolts, however, are incapable of swiveling and maintaining structural integrity under off-axis horizontal loads.